This invention has to do with dispenser pumps for dispensing discrete doses of a flowable material from a container on which the pump is fitted. The present proposals have particular relevance to dispenser pumps for use with viscous or pasty materials. They are also relevant when material to be dispensed needs to be protected from contact with air e.g. to prevent drying out or degradation. We particularly envisage that the invention may be embodied in a toothpaste dispenser.
In recent years toothpaste dispensers have become widely available in which a relatively large volume of paste is contained in a free standing container, and a piston-and-cylinder dispenser pump with a fixed discharge nozzle is provided at the top of the container to dispense a dose of toothpaste when the pump piston is depressed. Known pumps include arrangements for covering, blocking or shielding the discharge nozzle outlet between operations of the pump to keep the residual paste in the pump from drying out and to help separate the tail end of each dispensed dose from the nozzle tip. Toothpaste is extremely sticky and there are often problems in that slugs of paste issuing forth are not cleanly cut off, leading to toothpaste being smeared over the outside of the nozzle tip by the cover arrangement which is precisely the opposite of what is wanted.
The aim here is to propose new and useful dispenser pumps including a novel arrangement for blocking a discharge nozzle of the pump. A particular aim is to provide a pump which is for use with materials of the kinds mentioned above e.g. toothpaste.
In general terms, a dispenser pump of the relevant kind has a pump chamber whose volume is alterable in a pumping stroke by relative movement between a body of the pump and a plunger which is reciprocable relative to the body by hand actuation. Typically the plunger has a piston which works in a cylinder of the pump body, the piston and cylinder defining a pump chamber between them. An inlet is provided for flowable material to enter the pump chamber from a container to which the pump is secured, and an outlet of the pump chamber leads to a discharge passage which extends along a discharge nozzle to an external nozzle opening. Usually a one-way inlet valve is necessary and a one-way discharge valve is preferred.
A blocking element is provided, dimensioned to close off the discharge passage and arranged for guided movement transverse to the discharge passage between blocked and open positions. Preferably the blocking element traverses the discharge passage at a blocking location which is at or adjacent the external nozzle opening. The discharge nozzle construction includes a guide track leading around a bend to the blocking location. Preferably this bend or angle is substantially in longitudinal register with the blocking location. An elongate drive connector extends along this guide track, and is longitudinally slidable relative to it. This connector has a proximal part connected to the pump plunger, so that operation of the pump by moving the plunger relative to the pump body drives longitudinal movement of the drive connector along the guide track. A distal portion of the drive connector acts on the blocking element, preferably by being joined to or integral with it. The drive connector is also flexible, so as to be able to negotiate the bend in the guide track. By these means, operation of the pump by moving the plunger relative to the body drives movement of the blocking element across the discharge passage between the blocked and open positions.
By having the distal part of the drive connector joined to or integral with the blocking element, it can both push and pull the blocking element. Correspondingly, it is preferred that the proximal part of the drive connector is connected to the pump plunger in such a way that the two directions of plunger movement positively drive respectively the opening and closing of the discharge passage. The drive connector may include one or more non-flexing parts which do not pass around a bend and are thickened or reinforced relative to the flexing part(s), helping to avoid buckling under longitudinal compression.
The guide track preferably has a portion which extends alongside the discharge passage, leading around a distal bend to a transverse portion adjacent the blocking location. Guide track engagement at the outside of the bend, preferably by one or more curved elements, enables transverse action of the blocking element by pushing. Guide track engagement on the inside of the bend enables transverse action of the blocking element by pulling. Preferably both are present.
In preferred pumps the discharge nozzle extends generally transversely to the direction of the plunger action. In this situation the guide track may have a proximal corner which is between a longitudinal portion extending along the discharge nozzle and a proximal portion extending in the plunger""s direction of action. Again, guide track engagements to the inside and outside of such a corner enable pulling and pushing actions of the connector respectively and are preferably combined.
By these means, plunger movement in one direction may drive movement of the blocking element relative to the transversally-extending discharge passage in substantially the opposite direction.
Even when the discharge nozzle and plunger action are mutually transverse, it is possible to avoid the need for the drive connector to flex around more than one corner. This may be desirable because it reduces the longitudinal extent of the connector required to be flexible, and therefore reduces any tendency for it to buckle under compression. A way of achieving this is by having a coupling between the plunger action and the drive connector proximal end which is pivoted around an axis perpendicular to the plunger axis and to the guide track, the coupling and the proximal end of the drive connector being joined (preferably flexibly) at a joint substantially at a tangent point of the drive connector with respect to the coupling""s pivot axis. Such a coupling may for example be comprised in a pivoted actuating lever for the dispenser pump which acts on both the pump plunger stem and the drive connector for the blocking element.
A preferred disposition of the pump for these purposes, as indeed for the others, has the pump arranged with its plunger axis generally upright at the back of the dispenser, the discharge passage extending from the outlet at the bottom of the pump, up in front of the pump and then forwardly along the discharge nozzle to the discharge opening. The discharge nozzle is preferably at substantially the same height at the actuating portion at the top of the pump plunger.
A preferred form of the flexible elongate drive connector is a strip or tongue form, since this flexes more readily in one sense than in the perpendicular sense, facilitating guiding. It is generally convenient to arrange all guide track bends to be in one plane. A strip-form connector is also easy to form in plastics material. It may be formed as an integral projection on one of the pump components e.g. a plunger part. Furthermore the blocking element may itself be an integral continuation of the drive connector, e.g. an end thereof.
A blocking element which is a continuation of a flexible connector strip may itself pass around a corner of the guide track adjacent the blocking location, reducing the transverse dimension required for the nozzle. The blocking element may therefore also be flexible.
For a strip-form connector the guide track is preferably an elongate slot. A suitable track may be formed between complementarily-shaped opposed surfaces of two discharge nozzle components.
Means may be provided for reducing friction along the guide track. One or both components, preferably at least the connector, may be made from low-friction material or provided with a friction-reducing coating. A guide track for a strip-form connector can have one or more localised surface projections e.g. ribs to engage the connector with reduced contact area.
A preferred refinement of the pump assures at least partial opening of the discharge passage before the pump pressurizes the material in it. This is achievable by connecting the drive connector to an actuating part of the pump plunger such as a button or lever, and providing some lost motion in the connection between the actuating part and a piston part, so that driving of the piston begins only after some movement of the blocking element away from the blocked position.
As suggested above, a preferred embodiment of the invention is a toothpaste dispenser in which the dispenser is mounted at the top of a container for toothpaste adapted for airless dispensing e.g. by a container base in the form of a follower piston which rises up the container as material is dispensed, or by means of a flexible container or flexible container liner which gradually collapses as material is dispensed.
Combining various preferred features disclosed above, a preferred dispenser pump of such a toothpaste dispenser is as follows. The fixed pump body incorporates a fixed discharge nozzle projecting laterally. The pump plunger carries a piston operable in a cylinder of the pump body, with the plunger axis generally upright. The pump chamber inlet is into the bottom of the cylinder through a pump body base spanning the top of the container. The pump chamber outlet opens downwardly from the pump chamber e.g. into a annular discharge space leading to an initial riser portion of the discharge passage alongside the pump cylinder and them round an angle into a transverse portion of the discharge passage in the projecting discharge nozzle. The discharge nozzle includes inner and outer nozzle parts which fit together to define between them a guide track extending along the discharge nozzle and round a distal bend adjacent its end to open transversely onto the discharge passage adjacent its exterior opening.
In one version the inner end of the guide track bends inwardly and down around the angle between the first and second parts of the discharge passage, and accesses the side of the moveable plunger. A flexible strip is attached to the side of the plungerxe2x80x94e.g. formed integrally with itxe2x80x94and extends along the guide track up around the inside bend, along the nozzle and down out of the guide track""s distal opening to act across the discharge passage.
In another version a pivoted coupling is provided, connected to both the flexible strip and the pump plunger so that no inside bend of the strip is required.
The end of the strip fully blocks the discharge passage in the raised position of the plunger; its end edge may then seat in a recess on an opposing lower side of the discharge passage. Depression of the plunger pulls the strip along the guide track, flexing as it passes round the bend(s) and drawing the end blocking portion up out of the discharge passage and at least partially into the distal bend of the guide track. On release the plunger rises under the force of a restoring spring, pushing the flexible strip back along the guide track and its tip back across the discharge passage adjacent the nozzle opening to close it off. The closeness of fit of the strip in the guide track can be selected, along with suitable thickness of the strip, to enable this pushing effect without kinking or crumpling of the strip.
Embodiments of these proposals are now described by way of example.